Aerodynamic Modeling and System Identification from Flight Data

Abstract

System identification is fundamental to modeling of any observed dynamic process. This overview presentation brings out why and what system identification is as applied to flight vehicles. A historical background is briefly provided, tracing the developments to the 18th Century and early flight experiments in 1920s. Transition from classical to modern methods is brought out, highlighting the unified Quad-M approach to flight vehicle system identification that has evolved over the last three decades. Various aspects of kinematic consistency checking of recorded flight data and typical problems encountered are covered in detail. This is followed by several advanced examples pertaining to aerodynamic databases, covering (1) modeling at extreme flight conditions of large sideslip angles and stall hysteresis, (2) proof-of-match for critical flight phases, and (3) Phoenix RLV demonstrator. At the end, re-emerging aspects of recursive parameter estimation are briefly presented. The paper is concluded by indicating the possible future directions of work.